Business Insider attended the conference at the Bournemouth International Centre, and the mood was strange. Farage's on-stage cries of "we won!" and James' promise to transform UKIP into the official opposition had the hundreds of members and activists in attendance on their feet. But the room was also occupied by two pretty huge elephants.

The first of these was that Farage's departure is a huge blow to the party. The divisive but undeniably charismatic MEP, adored by party members, was the centre of attention throughout. "My wife was never interested in politics, but Nigel changed that," one activist said to Business Insider. "He's just not like every other politician you see on TV."

That is not to say James is not popular among the party's 37,000+ membership. She is very popular.

"We need someone who is credible who can speak to the country. Nobody else [other than James] is credible," a party activist from Oxford told me. Arron Banks, the party's millionaire donor, told Business Insider he was "delighted" to see James elected.

Trump is very personable. I watched him and he is brilliant at dealing with people, ordinary people. I don't agree with everything that he says but I can see why people vote for him.

But, at least at the moment, James is an unknown to the wider public. When Farage enters a room (or the Royal Exeter Hotel bar), love him or loathe him, all eyes are on him. James simply does not boast that kind of profile. The fact she refused to take part in all hustings in the run-up to the campaign likely did not help boost her profile, either.

As for Farage, it is unlikely he will be off our screens anytime soon. He told us he has plans to go back to the US where he controversially appeared alongside Republican Presidential candidate Donald Trump last month.

"Trump is very personable," he said. "I watched him and he is brilliant at dealing with people, ordinary people. I don't agree with everything that he says but I can see why people vote for him."

"I won't miss party politics ... I might join the Labour Party. There could be a spot at the top for me there," he said, jokingly.

Farage shared a story about how Banks, who donated £1 million (approximately $1.3 million) to the party in 2014, was so confident about the referendum result the day before it was announced that he bought an advertisement in the next morning's Telegraph newspaper to say thanks to Farage for spearheading the Brexit movement.

Farage admitted he was not quite as confident, but said he saw a Leave victory coming because Remain focused on "how terrible it would be to leave" rather than the positives on staying.

Former leader of UKIP Nigel Farage (R) holds a press conference with party donor Arron Banks on October 1, 2014 in Bristol, England.
Matt Cardy/Getty Image

Another issue facing the anti-EU party is disruption among its highest-ranking members. The party arrived in Bournemouth last weekend after weeks of bitter in-fighting after the initial leadership favourite, Steven Woolfe, had been barred from standing in the contest due to submitting his application after the deadline.

Leadership candidate Elizabeth Jones, who ended up receiving 6.7% of the vote, was in defiant mood when we spoke to her about the row. "I don't even know why there was a rift. I cannot remember it started. I'm not interested in factions," she said.

But it cannot be denied that James has some pretty gaping wounds to heal before the party can realistically work towards becoming Britain's opposition.

Then there was the issue of defections. On the morning of the announcement, a party official paid a visit to the press room and asked: "anyone else defected?" He was referring to Jonathan Stanley and Farage's former aide Alex Philips who had joined the Conservatives on the eve of the conference.

"People come and go" is what an activist told me when I asked him if he was worried about more defections. But with the referendum won and Theresa May promising to deliver policies that appear in the UKIP's own manifesto, like the re-introduction of grammar schools, there is the very real risk that the Tory party under new leadership will become a more appealing home for aspiring right-wing politicians than UKIP.

Yet, despite these concerns, most members remain optimistic.

"A huge sea of change is coming ... Keep your eye on May 5," an activist told me, referring to the next wave of local council elections which will take place in May 2017.

James also told the party membership: "Mrs. May, if you're watching, keep an eye on us. We are the opposition party in waiting."

The current electoral system means UKIP will face a massive uphill battle to win more seats in 2020. But, with Labour flirting with total collapse and May's government directionless when it comes to delivering Brexit, you would be foolish to write off UKIP.

At this rate, the public mood heading into 2020 could well be one of anger and disenchantment — ideal conditions for a populist third-party to grow and upset the odds once again.